Transmit-receive port for half-duplex transceivers

ABSTRACT

A half-duplex transceiver includes an antenna, antenna-side transformer windings coupled to the antenna, and a low-noise amplifier coupled to the antenna by the antenna-side transformer windings.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.16/428,471, filed on May 3, 2019, which is hereby incorporated herein byreference in its entirety.

BACKGROUND

A number of communication systems including, but not limited to, digitalwireless communication systems, wired communication systems, andassociated applications utilize half-duplex transceivers forcommunication purposes. In a typical half-duplex transceiver, data istransmitted and received at different time periods. In certainhalf-duplex transceivers, various wireless transmission protocols (e.g.,802.11b/g WiFi) combine a transmit port and a receive port (theresultant port being a “Tx-Rx port”) on the transceiver in order to freean additional pin. The Tx-Rx port is coupled to an antenna, for exampleby a bond wire coupling, to transmit and receive wireless signals.During the time periods in which the transceiver is configured toreceive wireless signals, such received signals are transmitted from theantenna to an amplifier (e.g., a low-noise amplifier (LNA)) by way of acapacitive coupling on a secondary side of a power amplifier baluntransformer. The capacitive coupling serves as part of a matchingnetwork between the antenna and the LNA. However, the capacitivecoupling increases the noise figure (or the degradation ofsignal-to-noise ratio (SNR)) and is sensitive to variations in bond wireinductance.

SUMMARY

In accordance with at least one example of the disclosure, a half-duplextransceiver includes an antenna, antenna-side transformer windingscoupled to the antenna, and a low-noise amplifier coupled to the antennaby the antenna-side transformer windings.

In accordance with another example of the disclosure, a half-duplextransceiver includes an antenna and antenna-side transformer windingscoupled to the antenna. The half-duplex transceiver is configured tooperate in a receive mode in which a low-noise amplifier is coupled tothe antenna by the antenna-side transformer windings.

In accordance with yet another example of the disclosure, a method ofoperating a half-duplex transceiver including an antenna coupled toantenna-side transformer windings includes operating the half-duplextransceiver in a receive mode by coupling a low-noise amplifier to theantenna by the antenna-side transformer windings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of various examples, reference will now bemade to the accompanying drawings in which:

FIG. 1 shows a block diagram of an example communication system inaccordance with various examples;

FIG. 2 shows a block diagram of a half-duplex transceiver includingcircuit schematic elements in accordance with various examples;

FIG. 3 shows a circuit schematic diagram of a half-duplex transceiver inaccordance with various examples;

FIG. 4 shows an exemplary Smith chart in accordance with variousexamples;

FIG. 5 shows an exemplary graph of noise factor and power loss as afunction of frequency in accordance with various examples; and

FIG. 6 shows a flow chart of a method for operating a half-duplextransceiver in accordance with various examples.

DETAILED DESCRIPTION

In addition to improving noise performance by mitigating the increasednoise figure caused by a capacitive coupling between the antenna and theLNA explained above, it is also desirable to reduce power consumption ofhalf-duplex wireless transceivers. Examples of the present disclosureaddress the foregoing by utilizing an inductor as a coupling between theantenna and the LNA. In examples, the inductor is at least part of thematching network that transforms the impedance of the antenna to anoptimum source impedance for the LNA.

The inductor couples to the antenna through the secondary- orantenna-side windings of the power amplifier balun transformer. Theinductor is also coupled to the LNA. By replacing the capacitivematching network with an inductive matching network, the noise figure isdecreased. For example, and as will be explained further below withrespect to FIG. 4, using an inductor as a coupling between the antennaand the LNA results in a source impedance value that intersects a noisecircle having a lower value than that which would be available whenusing a capacitor as the coupling device.

In some examples, the matching network includes components in additionto the inductor coupling the antenna to the LNA, which move the sourceimpedance closer to Gmin (e.g., an optimum source impedance). When usingan inductor as a coupling between the antenna and the LNA, theadditional components of the matching network are able to add lessadditional inductance to approximate Gmin than the additional componentsof a matching network when using a capacitor as a coupling device.Further, loss due to the received signal coupling to the amplifier-sidewindings of the balun transformer is reduced, which effectivelyincreases the gain of the LNA. As a result, for a similar gain and noiseperformance, the half-duplex transceiver current consumption is reduced.The half-duplex transceiver is also less sensitive to variations in bondwire inductance because this value is a relatively small percentage ofthe overall inductance of the matching network, including the inductoras a coupling between the antenna and the LNA, which is explained infurther detail below.

FIG. 1 depicts a block diagram of a communication system 100, wherevarious examples can be implemented. In this broad level representationof FIG. 1, the communication system 100 is shown as a transceiver,designed to transmit and receive signals. Examples of the communicationsystem 100 include, but are not limited to, a subscriber station, awireless device, a cellular telephone, a cordless telephone, a handheldtwo-way radio, a Session Initiation Protocol (SIP) phone, a wirelesslocal loop (WLL) station, a personal digital assistant (PDA), a handhelddevice having wireless connection capability, other processing deviceconnected to a wireless modem fixed telephone systems, mobile computeror media players with communication capabilities, and othercommunication devices. The communication system 100 includes atransceiver subsystem 102 including a transmitter subsystem 104 and areceiver subsystem 106, and an antenna 110. In an example, thecommunication system 100 also includes a local oscillator (LO) subsystem108, which provides a LO signal (or a signal derived from a LO signal)to the transmitter subsystem 104 and the receiver subsystem 106.

In an example, the transceiver subsystem 102 is a half-duplextransceiver that includes the transmitter subsystem 104 for transmittingdata and the receiver subsystem 106 for receiving data. Some componentsof the transmitter subsystem 104 and the receiver subsystem 106 may be acommon component. The transmitter subsystem 104 and the receiversubsystem 106 are configured to operate at different time intervals fortransmission and reception of data, respectively. For example, during atransmission phase of the transceiver subsystem 102, the transmittersubsystem 104 is in an active state and the receiver subsystem 106 is inan inactive state. During a reception phase of the transceiver subsystem102, the receiver subsystem 106 is in the active state and thetransmitter subsystem 104 is in the inactive state.

FIG. 2 shows a half-duplex transceiver 200 that includes the transmittersubsystem 104 and the receiver subsystem 106 in further detail, withcertain circuit elements being depicted. The transmitter subsystem 104includes a transmitter chain 211 that is coupled to a power amplifier212. The power amplifier 212 is configured to produce a differentialsignal that is applied to amplifier-side windings 208 of a baluntransformer 206. The balun transformer 206 also includes antenna-sidewindings 210, which are coupled to an antenna 202. When the poweramplifier 212 applies a differential signal to the amplifier-sidewindings 208, the balun transformer 206 operates to convert thedifferential signal to a single-ended signal in the antenna-sidewindings 210, which is then transmitted via the antenna 202.

The receiver subsystem 106 includes a receiver chain 223 that is coupledto a low-noise amplifier (LNA) 222. Examples of this disclosure do notlimit the LNA 222 to any particular topology or design; rather, the LNA222 may include a variety of known topologies, such as common gate orcommon source with source degeneration, which is shown in FIG. 3. TheLNA 222 is coupled to a matching network 216 and amplifies RF signalsreceived from the matching network 216. The LNA 222 and the matchingnetwork 216 are referred to separately in FIG. 2 to illustrate thedistinction between amplification functionality (e.g., carried out bythe LNA 222) and impedance-matching functionality (e.g., carried out bythe matching network 216). However, it should be appreciated thatcertain components (e.g., components such as transistors and inductors,which are described further below with respect to FIG. 3) contribute toboth the amplification functionality of the LNA 222 and toimpedance-matching functionality of the matching network 216. Thus,although the LNA 222 and the matching network 216 are shown separatelyin FIG. 2, sub-components of these functional blocks are not necessarilymutually exclusive or distinct.

The matching network 216 is in turn coupled to the antenna-side windings210. A transmit-receive switch (Tx-Rx switch) 214 is configured toselectively couple a node 215 between the antenna-side windings 210 andthe matching network 216 to a ground node. In this example, the Tx-Rxswitch 214 is an n-type metal-oxide-semiconductor field-effecttransistor (MOSFET). Thus, in an example, when a signal (EN) applied tothe gate of the Tx-Rx switch 214 is asserted, the Tx-Rx switch 214conducts and couples the node 215 to the ground node. Conversely, whenthe EN signal is de-asserted, the Tx-Rx switch 214 does not conduct andisolates the node 215 from the ground node.

As explained above, various wireless transmission protocols (e.g.,802.11b/g WiFi) combine a transmit port and a receive port (theresultant port being a “Tx-Rx port”) on the transceiver in order to freean additional pin. In the example of FIG. 2, the antenna 202 is coupledto such a single Tx-Rx port 203. The examples of this disclosure may beapplied to any half-duplex system.

The transmitter subsystem 104 is active during time periods in which thehalf-duplex transceiver 200 is transmitting. To effect transmission of asignal through the antenna 202, the transmitter chain 211 includessuitable logic, circuitry, and/or executable instructions to enablegeneration of RF transmit signals. The generated RF transmit signalsfrom the transmitter chain 211 are coupled to the input of the poweramplifier 212. The power amplifier 212 contains suitable logic,circuitry, and/or executable instructions to amplify the signal at itsinput. In an example, the RF transmit signals are transmitted by theantenna 202 at a higher power level than that of an RF signal receivedat the antenna 202, and thus the power amplifier 212 receives as inputthe RF transmit signals, amplifies the RF transmit signals, and providesthe amplified RF transmit signals to the amplifier-side windings 208 ofthe balun transformer 206. The amplifier-side windings 208 transferelectrical energy to the antenna-side windings 210 (e.g., by magneticcoupling), which in turn provides the signal to the antenna 202 forwireless transmission.

During time periods in which the half-duplex transceiver 200 istransmitting, the EN signal is asserted and thus the Tx-Rx switch 214conducts and couples the node 215 to the ground node. The amplitude ofthe amplified RF transmit signals is large, which could for exampledamage the LNA 222. To avoid such damage, the Tx-Rx switch 214sufficiently decouples the antenna-side windings 210 from the matchingnetwork 216, and thus the LNA, by providing a connection from theantenna-side windings 210 to the ground node.

During time periods in which the half-duplex transmitter 200 isreceiving, the EN signal is de-asserted and thus the Tx-Rx switch 214does not conduct and isolates the node 215 from the ground node. As aresult, the antenna-side windings 210 are coupled to the matchingnetwork 216, and in turn to the LNA 222. Thus, the antenna-side windings210 function as an inductive signal coupling since the antenna 202 iscoupled to the LNA 222 by the antenna-side windings 210. RF signals arereceived at the antenna 202 and transferred through the antenna-sidewindings 210 and the matching network 216 to the LNA 222. The LNA 222amplifies the received RF signals, and the amplified received RF signalsare provided at the output of the LNA 222 to the receiver chain 223. Thereceiver chain 223 includes suitable logic, circuitry, and/or executableinstructions to enable processing of the received RF signals.

The matching network 216 is configured to transfer the received RFsignals from the antenna 202 to the LNA 222 while transforming theimpedance of the antenna 202 to an optimum source impedance for the LNA222. It is desirable to design the matching network 216 so as to reducethe noise factor and current consumption of the receiver subsystem 106.It is further desirable to reduce sensitivity to variations in bond wireinductance. These factors will be discussed in further detail below withrespect to FIG. 3.

FIG. 3 shows an example circuit schematic diagram of a half-duplextransceiver 300. Like the half-duplex transceiver 200 of FIG. 2, thehalf-duplex transceiver 300 also includes the transmitter subsystem 104and the receiver subsystem 106. In FIG. 3, elements with like numbers tothose described with respect to FIG. 2 function in a like manner,including the transmitter chain 211, the power amplifier 212, the baluntransformer 206 (and its windings 208, 210), the antenna 202, the Tx-Rxport 203, the Tx-Rx switch 214, the LNA 222, and the receiver chain 223.

The half-duplex transceiver 300 further demonstrates the presence ofbond wire inductance, represented by the inductor 304 coupled to theantenna 202 and the antenna-side windings 210 of the balun transformer206. A bias voltage source 318 and a bias resistor 320 are coupled tothe input of the LNA 222 and are configured to provide a direct current(DC) voltage at the input of the LNA 222 to allow for properamplification of the received RF signals. In this example, the LNA 222includes a first n-type MOSFET 322 and a second n-type MOSFET 323, eachhaving a gate, a source, and a drain. The source of the first n-typeMOSFET 322 is coupled to a source degeneration inductor 324, which is inturn coupled to a ground node. The gate of the first n-type MOSFET 322is coupled to a gate inductor 321 and functions as the input of the LNA222, while the drain of the first n-type MOSFET 322 is coupled to thesource of the second n-type MOSFET 323. The gate of the second n-typeMOSFET 323 is coupled to a voltage source, which is not shown forsimplicity but provides a voltage V_(b) to bias the gate of the secondn-type MOSFET 323. The drain of the second n-type MOSFET 323 is coupledto the receiver chain 223 and provides the amplified received RF signalsto the receiver chain 223 for additional processing. The drain of thesecond n-type MOSFET 323 is also coupled to a load inductor 325, whichis in turn coupled to a supply voltage node, represented by V_(DD) inthis example. As explained above with respect to FIG. 2, the componentsof the LNA 222 may also contribute to impedance-matching functionalityof the receiver subsystem 106. For example, the gate inductor 321 andthe source degeneration inductor 324 provide impedance-matchingfunctionality in addition to being part of the LNA 222 topology.Similarly, the n-type MOSFETs 322, 323 also provide impedance-matchingfunctionality in addition to being part of the LNA 222 topology.

The first n-type MOSFET 322 provides a current proportional to itstransconductance and quality factor of the matching network 216, whichin this example is represented by the gate inductor 321 and the sourcedegeneration inductor 324. This amplified current flows through thesecond n-type MOSFET 323 and into the load inductor 325, resulting in avoltage gain at Vout relative to the signal voltage at the gate of then-type MOSFET 322, which is received and processed by the receiver chain223. Thus, the gain of the LNA 222 is impacted by the quality factor ofthe matching network 216 (e.g., the gate inductor 321 and the sourcedegeneration inductor 324) and the load inductor 325 as well as thetransconductance of the n-type MOSFET 322. As explained above, since theinductance required to be provided by the matching network 216 toachieve Gmin is lower when using the antenna-side windings 210,functioning as an inductor, as a signal coupling element than when usinga capacitive coupling element, the gain of the LNA 222 is also improved.

In accordance with an example, signal coupling from the antenna 202 tothe LNA 222 is provided by the antenna-side windings 210, functioning asan inductor. In particular, the antenna-side windings 210 are coupled tothe input of the LNA 222 (e.g., the gate of the first n-type MOSFET 322by way of gate inductor 321) and to the antenna 202.

As explained above, a bond wire may be used to couple the antenna 202 tothe antenna-side windings 210 of the balun transformer 206. Such a bondwire coupling has an inductance component 304 of its own that may varyas a function of process tolerance, impacting the noise performance ofthe receiver subsystem 106. However, the sum value of the antenna-sidewindings 210 and the gate inductor 321 is much greater than the bondwire inductance 304. Thus, by using the antenna-side windings 210 as thesignal coupling from the antenna 202 to the input of the LNA 222,variations in bond wire inductance 304 have a lessened impact on noiseperformance of the receiver subsystem 106. In one example, theantenna-side windings 210 and the inductor 321 may have an inductance ofapproximately 4 nH, while the bond wire inductance 304 is approximately1 nH and varies up to +/−10% (0.1 nH) based on the frequency of receivedRF signals. Thus, the overall inductance in the signal path from theantenna 202 to the LNA 222 varies from approximately 4.9-5.1 nH, whichis only a variation of 2%. As a result of the lessened impact ofvariations in bond wire inductance 304, overall noise performance of thereceiver subsystem 106 is improved over a range of variation of bondwire inductance 304.

In addition to reducing performance dependencies on the variations inbond wire inductance 304, using the inductor 321 as the signal couplingfrom the antenna-side windings 210 to the input of the LNA 222 alsoimproves the noise factor of the LNA 222 as well as the currentconsumption of the receiver subsystem 106, as explained further withrespect to FIGS. 4 and 5. FIG. 4 shows a Smith chart 400 having noisefigure circles 402, 404, 406, 408 that correspond to LNA 222 noisefigures of 2, 2.5, 3, and 3.5 dB, respectively. The Smith chart 400includes an impedance curve 410 as a function of frequency (e.g.,2.3-2.5 GHz) that corresponds to “Gmin” for the LNA 222. The Smith chart400 also includes an impedance curve 412 as a function of frequency thatcorresponds to utilizing the antenna-side windings 210 as the signalcoupling between the antenna 202 and the input of the LNA 222. Finally,the Smith chart 400 includes an impedance curve 414 as a function offrequency that corresponds to utilizing a capacitor as the signalcoupling between the antenna 202 and the input of the LNA 222.

As can be seen, the impedance curve 412 corresponding to theantenna-side windings 210, functioning as an inductive signal coupling,is approximately 1 dB better than the impedance curve 414 correspondingto the capacitive signal coupling in terms of noise figure. Further, animpedance curve being farther away from the noise figure circle 402,which represents an optimal source impedance for the LNA 222, requiresmore inductance to rotate the impedance curve into the noise figurecircle 402. In examples, increasing inductance in a matching networkintroduces additional noise to the RF signals that propagate through thematching network. Thus, to achieve the optimal source impedance for theLNA 222, the matching network using the capacitive signal couplingrequires more inductance, and introduces more noise, than the matchingnetwork using the inductive signal coupling of the antenna-side windings210.

In addition to the improved noise performance achieved by using theinductive signal coupling of the antenna-side windings 210 between theantenna 202 and the input of the LNA 222, current consumption of thereceiver subsystem 106 is also reduced. FIG. 5 shows a set of waveforms500 that demonstrate the noise factor and power loss as a function offrequency that result from both using a capacitive signal coupling andusing inductive signal coupling of the antenna-side windings 210. Thewaveforms 500 include a waveform 502 that shows noise factor as afunction of frequency when using a capacitive signal coupling and awaveform 504 that shows noise factor as a function of frequency for aninductive signal coupling, such as the inductive signal coupling of theantenna-side windings 210 as explained above. The waveforms 500 alsoinclude a waveform 506 that shows power loss due to the received signalcoupling to the amplifier-side windings 210 of the balun transformer 206as a function of frequency for an inductive signal coupling, such as theinductive signal coupling of the antenna-side windings 210 as explainedabove. The waveforms 500 further include a waveform 508 that shows powerloss due to the received signal coupling to the amplifier-side windings210 of the balun transformer 206 as a function of frequency for acapacitive signal coupling.

As shown in FIG. 5, for approximately equivalent noise factorperformance at 2.4 GHz (e.g., the intersection of waveforms 502, 504),the power loss for the inductive signal coupling, shown by waveform 506,is less than the power loss for the capacitive signal coupling, shown bywaveform 508. Due to the inductive signal coupling providing improvednoise performance, as demonstrated in FIG. 4 and explained above, theLNA 222 current consumption (and thus half-duplex transceiver 300current consumption) is reduced, while still providing comparable noiseperformance to half-duplex transceivers using a capacitive signalcoupling.

FIG. 6 shows a method 600 for operating a half-duplex transceiver (e.g.,half-duplex transceiver 300 described above). The half-duplextransceiver 300 includes an antenna 202 coupled to antenna-sidetransformer windings 210. The method 600 begins in block 602 withoperating the half-duplex transceiver 300 in a receive mode by couplinga low-noise amplifier (e.g., LNA 222) to the antenna 202 by theantenna-side transformer windings 210. In this way, an inductive signalcoupling is provided between the antenna 202 and the LNA 222, whichimproves performance of the half-duplex transceiver 300 as explainedabove. The method 600 optionally continues in block 604 with operatingthe half-duplex transceiver 300 in a transmit mode by de-coupling thelow-noise amplifier (e.g., LNA 222) from the antenna-side transformerwindings 210. As explained above, a transmit-receive switch 214 mayfacilitate operation in such transmit and receive modes. For example,during the receive mode, the transmit-receive switch 214 is controlledso as to not conduct, which couples the antenna-side transformerwindings 210 to the LNA 222. During the transmit mode, thetransmit-receive switch 214 is controlled so as to conduct, whichcouples a node 215 between the antenna-side transformer windings 210 andthe LNA 222 to a ground node, effectively de-coupling the LNA 222 fromthe antenna-side transformer windings 210.

In the foregoing discussion and in the claims, the terms “including” and“comprising” are used in an open-ended fashion, and thus should beinterpreted to mean “including, but not limited to . . . .” Also, theterm “couple” or “couples” is intended to mean either an indirect ordirect connection. Thus, if a first device couples to a second device,that connection may be through a direct connection or through anindirect connection via other devices and connections. Similarly, adevice that is coupled between a first component or location and asecond component or location may be through a direct connection orthrough an indirect connection via other devices and connections. Anelement or feature that is “configured to” perform a task or functionmay be configured (e.g., programmed or structurally designed) at a timeof manufacturing by a manufacturer to perform the function and/or may beconfigurable (or re-configurable) by a user after manufacturing toperform the function and/or other additional or alternative functions.The configuring may be through firmware and/or software programming ofthe device, through a construction and/or layout of hardware componentsand interconnections of the device, or a combination thereof.Additionally, uses of the phrases “ground” or similar in the foregoingdiscussion are intended to include a chassis ground, an Earth ground, afloating ground, a virtual ground, a digital ground, a common ground,and/or any other form of ground connection applicable to, or suitablefor, the teachings of the present disclosure. Unless otherwise stated,“about,” “approximately,” or “substantially” preceding a valuemeans+/−10 percent of the stated value.

The above discussion is meant to be illustrative of the principles andvarious embodiments of the present disclosure. Numerous variations andmodifications will become apparent to those skilled in the art once theabove disclosure is fully appreciated. It is intended that the followingclaims be interpreted to embrace all such variations and modifications.

What is claimed is:
 1. A half-duplex transceiver, comprising: anantenna; antenna-side transformer windings coupled to the antenna; alow-noise amplifier having an input; an inductive matching networkconnecting the input of the low-noise amplifier to the antenna-sidetransformer windings; a power amplifier; amplifier-side transformerwindings coupled to the power amplifier, the amplifier-side transformerwindings magnetically coupled to the antenna-side transformer winding; atransmit-receive switch connected to a node between the antenna-sidetransformer windings and the input of the low-noise amplifier, and to aground node, the transmit-receive switch configured to selectivelyconduct and connect the node to ground; wherein the half-duplextransceiver is configured to operate in a transmit mode and a receivemode and wherein the transmit-receive switch is configured to conduct inthe transmit mode and to not conduct in the receive mode.
 2. Thehalf-duplex transceiver of claim 1, wherein the transmit-receive switchcomprises an n-type metal-oxide-semiconductor field-effect transistor(MOSFET).
 3. The half-duplex transceiver of claim 1, wherein thelow-noise amplifier comprises an n-type metal-oxide-semiconductorfield-effect transistor (MOSFET) and an inductor coupled to a gate ofthe n-type MOSFET and to the antenna-side transformer windings.
 4. Thehalf-duplex transceiver of claim 3, further comprising: a bias voltagesource; and a bias resistor coupled to the bias voltage source, theinductor, and the gate of the n-type MOSFET.
 5. A half-duplextransceiver, comprising: an antenna; antenna-side transformer windingscoupled to the antenna; a low-noise amplifier having an input; atransmit-receive switch connected between a ground node and to a nodebetween the antenna-side transformer windings and the input of the lownoise amplifier; and an inductive matching network; wherein thehalf-duplex transceiver is configured to operate in a receive mode inwhich the input of the low-noise amplifier is connected to theantenna-side transformer windings through the inductive matchingnetwork; and wherein the half-duplex transceiver is configured tooperate in a transmit mode in which the low-noise amplifier isde-coupled from the antenna-side transformer windings by thetransmit-receive switch coupling the input of the low-noise amplifier tothe ground node.
 6. The half-duplex transceiver of claim 5, wherein thetransmit-receive switch is configured to not conduct in the receivemode.
 7. The half-duplex transceiver of claim 5, wherein thetransmit-receive switch comprises an n-type metal-oxide-semiconductorfield-effect transistor (MOSFET).
 8. The half-duplex transceiver ofclaim 5, further comprising: a power amplifier; and amplifier-sidetransformer windings coupled to the power amplifier; wherein theamplifier-side transformer windings are magnetically coupled to theantenna-side transformer windings.
 9. The half-duplex transceiver ofclaim 5, wherein the low-noise amplifier comprises an n-typemetal-oxide-semiconductor field-effect transistor (MOSFET) having a gateat the input of the low-noise amplifier; and wherein the inductivematching network comprises a gate inductor is coupled between the gateof the n-type MOSFET and the antenna-side transformer windings.
 10. Thehalf-duplex transceiver of claim 9, further comprising: a bias voltagesource; and a bias resistor coupled to the bias voltage source, theinductor, and the gate of the n-type MOSFET.
 11. The half-duplextransceiver of claim 1, wherein the low-noise amplifier comprises: afirst n-type metal-oxide-semiconductor field-effect transistor (MOSFET)having a source coupled to a ground node, a drain, and a gate; and asecond MOSFET having a source coupled to the drain of the first MOSFET,a gate coupled to a voltage source, and a drain coupled to a supplyvoltage node; and wherein the inductive matching network comprises: agate inductor coupled between the antenna-side transformer windings andthe gate of the first MOSFET.
 12. The half-duplex transceiver of claim11, wherein the inductive matching network further comprises: a sourcedegeneration inductor coupling the source of the first MOSFET to theground node.
 13. The half-duplex transceiver of claim 12, wherein thelow-noise amplifier further comprises: a load inductor coupling thedrain of the second MOSFET to the supply voltage node.
 14. Thehalf-duplex transceiver of claim 5, wherein the low-noise amplifierfurther comprises: a second n-channel MOSFET having a source coupled toa drain of the first n-channel MOSFET, a gate coupled to a voltagesource, and a drain coupled to a supply voltage node.
 15. Thehalf-duplex transceiver of claim 14, wherein the inductive matchingnetwork further comprises: a source degeneration inductor coupling thesource of the first n-channel MOSFET to the ground node.
 16. Thehalf-duplex transceiver of claim 15, wherein the low-noise amplifierfurther comprises: a load inductor coupling the drain of the secondn-channel MOSFET to the supply voltage node.